The following is an excerpt from Chapter 45 of Kṛṣṇa Book, in which Srila Prabhupada describes that after hearing only once from the teacher, Sandipani Muni, Kṛṣṇa and Balarāma learned all the arts and sciences.

…So Kṛṣṇa and Balarāma, the Supreme Personality of Godhead, are the source of all kinds of knowledge, but because They were playing like ordinary human boys, They set the example so that everyone would receive knowledge from the right source. Thus They agreed to take knowledge from a spiritual master.

After hearing only once from the teacher, Kṛṣṇa and Balarāma learned all the arts and sciences. In sixty-four days and sixty-four nights They learned all the necessary arts that are required in human society. During daytime They took lessons on a subject from the teacher, and by nightfall, after having heard from the teacher, They were expert in that department of knowledge.